2 Replies
      Latest reply on Jun 13, 2019 11:21 PM by Vadim
      Vadim Level 1 Level 1 (0 points)

        This year’s WWDC session named “What’s New in Swift” has got the following sample code:


        let quantity = 10
        let formatString = NSLocalizedString(
          "You have %lld apples",
          comment: "Number of apples"
        label.text = String(format: formatString, quantity)


        This is the first time ever when I meet “%lld” as a specifier for an integer value.


        So what is a recommended specifier for the “Swift.Int” type? Is it “%d” or “%lld” and why? Thanks in advance!

        • Re: What is a correct way to specify Swift.Int: %d or %lld?
          OOPer Level 8 Level 8 (5,435 points)

          The format specifiers used in `String.init(format:)` are derived from `[NSString format:]` (or C's *

          `printf`) and described in this doc.


          Generally, `ll` stands for `long long`, which represents 64-bit integer in Apple's platforms. (Both in 32-bit and 64-bit.)

          And in Swift,  `long long` is equivalent to `Int64` (or `CLongLong`).


          So, use `%lld` for `Int64`.


          And `%d` takes C-`int`, which is equivalent to `Int32` (or `CInt`) in Swift. (Always represents 32-bit, both in 32-bit and 64-bit platforms.)


          `Swift.Int` is equivalent to C-`long` (or `long int` or `NSInteger`), which is 32-bit in 32-bit platforms and 64-bit in 64-bit platforms.

          And the right format for C-`long` is `%ld`.


          If you write your code only for 64-bit platforms, `%lld` and `%ld` are equivalent, but I recommend you to use `%ld` for `Swift.Int`.